Device for heating and cooling an enclosed chamber

ABSTRACT

The invention relates to a device for heating and cooling an enclosed chamber comprising a cooling pipe within which is mounted a heating conductor. The cooling pipe is in the form of a coil, preferably of bifilar construction. The cooling pipe has a branchpiece at each end outside the chamber, the branchpieces being spatically separated and from which the ends of the heating conductor are taken. The resistance of the ends of the heating conductor where it passes out of the chamber are of as low a resistance as possible.

United States Patent Hochschorner et al.

[ 1 Feb. 29, 1972 [54] DEVICE FOR HEATING AND COOLING AN ENCLOSED CHAMBER [72] Inventors: Paul Hochschorner, Frankenbach; Fritz Kielwein, Neckarsulm, both of Germany [73] Assignee: Telefunken Patentverwertungsgeselischaft m.b.H, Ulm am Danube, Germany [22] Filed: July 8, 1969 [21] Appl. No.: 839,904

[30] Foreign Application Priority Data July 27, 1968 Germany ..P 17 58 719.8

[52] U.S. Cl ..l65/48, 165/64, 165/169 [51] Int. Cl v ..F25b 29/00 [58] Field of Search .....165/48, 64, 169, 58; 219/306;

[56] References Cited UNITED STATES PATENTS 1,040,929 10/1912 Golden ..165/169 3,287,925 11/1966 Kane et al ..62/514 2,117,419 5/1938 Hamrick et al.. ..219/306 2,721,729 10/1955 Van Riper ..165/64 Primary Examiner-Charles Sukalo Attorney--Spencer & Kaye [57] ABSTRACT The invention relates to a device for heating and cooling an enclosed chamber comprising a cooling pipe within which is mounted a heating conductor. The cooling pipe is in the form of a coil, preferably of bifilar construction. The cooling pipe has a branchpiece at each end outside the chamber, the branchpieces being spatically separated and from which the ends of the heating conductor are taken. The resistance of the ends of the heating conductor where it passes out of the chamber are of as low a resistance as possible.

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SHEET 2 OF 3 Paul. Hochscho'rmr Fritz kiclwein FATENTED FEB 29 I972 sum 3 or a DEVICE FOR HEATING AND COOLING AN ENCLOSED CHAMBER BACKGROUND OF THE INVENTION The present invention relates to a device for heating and cooling an enclosed chamber with a heating system and a cooling system. In this case, the invention consists in that at least one heating element is mounted inside a pipe which is provided for supplying a cooling medium.

Devices for heating and cooling an enclosed chamber are frequently needed today for the manufacture of electrical components, such as thin-film and thick-film devices, diodes, transistors, integrated solid-state circuits and the like. Diffusion furnaces, alloying furnaces and high-vacuum vapor deposition installations must be heated and cooled and very often a specific time temperature function is prescribed. In many cases, it has to be possible to realize temperature ranges between about 200 and 1,000 C.

SUMMARY OF THE INVENTION According to the invention, there is provided a device for heating and cooling an enclosed chamber with a heating system and a cooling system, comprising a pipe for conveying a cooling medium and at least one heating conductor mounted inside said pipe.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in greater detail by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a known installation shown in section;

FIG. 2 shows the device according to the invention in section, and its use in a high-vacuum installation;

FIG. 3 shows a bifilar arrangement of the combined heating and cooling system, and

FIG. 4 is an enlarged detail of a portion of the cooling pipe and the heating element conveyed therein.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A known installation is illustrated in section in FIG. 1. In this installation a thin layer of aluminum, for example, is being vapor-deposited simultaneously on a large number of semiconductor wafers 1. The container 2 illustrated in FIG. 1 has a double wall 3, water being conveyed through the cavity 4 therein in order to cool the wall. The container, which is closed in a vacuum-tight manner, is evacuated by means of a backing pump 5, a diffusion pump 6 and a plate valve 7. Mounted in the container is a bell-shaped shield 8 which consists of thin-walled sheet metal and is carried by a cooling coil 9. A heating element 10 is wound helically over the outer face of the shield 8. The ends of the heating element 10 and of the cooling coil 9 are taken to the outside in a vacuum-tight manner and connected to a current source and to a pump delivering the cooling medium respectively. Mounted inside the bell-shaped shield 8, which surrounds the heating and cooling zone and hence the radiation chamber, is a domedsupporting member 11, to the concave surface of which there are secured semiconductor wafers 1 to be coated, for example. The coating source 12 is mounted opposite the semiconductor wafers, the coating material being caused to vaporize by means of the energy supplied by a heavy current transformer 13.

The heating and cooling device illustrated in FIG. 1 has the disadvantage that, if necessary, the heating winding has to be cooled down indirectly through the bell-shaped shield 8 which serves as a holder for the heating winding. The calorific power required is also relatively great in the arrangement described.

because the not inconsiderable mass of the holder has to be heated first. Furthennore, in the arrangement illustrated, the heating element is screened off from the radiation chamber because the electrical conductance of the heating element would change in an inadmissable manner if the material radiated from the coating source could also precipitate on the outer face of the conductor. A further disadvantage of the arrangement shown in FIG. 1 consists in that the connecting ends of the heating element and of the cooling coil have to be taken out of the container separately in a vacuumtight manner. vacuumtight ducts are relatively complicated, however, and increase the cost of manufacture of a vacuum-coating installation so that efforts are made to keep the number of ducts as low as possible.

The said disadvantages are overcome if the combined heating and cooling device according to the invention is used. The heating element now extends in the interior of the cooling pipe so that a holder for the heating coil is eliminated. If a cooling medium is pumped through the portion of the cavity in the cooling pipe left free by the heating conductor, the heating winding is cooled down directly. In the arrangement according to the invention, the gas present in the cooling pipe is also used as a heat transfer medium during the heating operation in order to heat up the tubular member. Since the heating conductor extends in the cooling pipe, only half as many vacuumtight ducts are needed for the new device as in the known device. Narrow metal strips which have an extremely low mass, and which are constructed in the form of straps, suffice to hold the cooling coil in which the heating conductor extends. In the new device, the deposition of impurities or layers on the outer surface of the heating element, which would alter the resistance value of the heating element in an undesirable manner, is completely out of the question. Moreover, anything which diffused out of the heating element does not reach the radiation chamber.

The upper portion of a high-vacuum installation in accordance with the invention is illustrated in FIG. 2. The parts already shown in FIG. 1 are omitted here. As in FIG. 1, the container 2 contains highly polished shielding plates 14 which consist of nickel for example. Mounted inside the container is a cooling coil 15 which is wound in the form of a spiral and which, as a whole, is in the form of a bell. A plain or domed supporting member 11 for the semiconductor wafers to be coated is again mounted in the area enclosed by the cooling coil. The ends of the cooling coil are taken through the cover 16 in a vacuumtight manner and end outside the container in the outlet of a branch piece 17. At the inlet side, this branchpiece 17 has two apertures, the heating conductor 10 being taken in a gastight manner through the one aperture while a connecting socket 18 for the supply of the cooling medium is connected to the other aperture. In the interior of the branchpiece, the heating conductor extends through the cavity in the cooling pipe and passes through the entire length of the cooling pipe. The basket-shaped or bell-shaped cooling coil is held in position by self-supporting, narrow metal strips 19, constructed in the form of straps.

The cross section of the heating conductor 10 preferably corresponding to about a quarter of the cross section of the cavity in the cooling pipe. The cooling pipe may be made of high-grade steel for example. Compressed air or liquid nitrogen have proved suitable as cooling media.

The manner in which the cooling coil is wound is illustrated in perspective in FIG. 3. In order to reduce the electrical load ing by the heating conductors, two cooling coils 20 and 21 are preferably selected, arranged as shown in FIG. 3, each cooling coil winding being bifilar and helical. Between each two adjacent windings of the one bifilar wound system there is a winding of the other bifilar wound system so that the two systems extend parallel to one another. In order to retain clarity, only the system 20 is shown in full in FIG. 3 while the second system 21 is indicated by chain lines. The ends of the two cooling coils are again welded in a vacuumtight manner in apertures in the cover 16. The narrow holding strips 19 for the combined heating and cooling systems are also illustrated in FIG. 3.

The heating conductor 10 taken through a cooling pipe 15 and illustrated in FIG. 4 preferably consists of a so-called miniature sheathed heating conductor. These miniature sheathed heating conductors have a metallic core 22, for example, of a nickel chrome alloy. This core is encased with an insulating material 23 which consists, for example, of barium oxide or of magnesium oxide. The outer surface of the insulation is in turn coated with a nickel chrome alloy (24). The core of the heating conductor is connected to a voltage source and the current flowing through the core heats the outer layer of the heating conductor through the insulating material. Through the residual gas present in the cooling pipe, the wall of the cooling pipe of high-quality steel is heated during the heating operation and in turn surrenders the heat to the environment.

The ends of the heating conductor taken out of the container consist of a material, the resistance value of which per unit of length is as low as possible. By this means, so-called cold ends" are obtained, the temperature of which is considerably below that of the actual heating conductor during the heating operation.

The heating and cooling device according to the invention is particularly suitable for vacuum-coating instations; it may, however, be used wherever containers or specific areas are heated and subsequently have to be cooled down again after the heating source has been switched off. it is also conceivable, however, that in order to adjust a specific temperature profile, the heating conductor may be heated and a cooling medium conveyed through the cooling tube simultaneously. This would be the case in particular if peaks in the temperature time curve had to be levelled off.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a device for heating and cooling a chamber volume for use with means for circulating a cooling medium through the device and means for heating the cooling medium, the improvement comprising in combination:

a. at least one pipe for conveying a circulating cooling medium and formed in the shape of helically wound coils:

b. an electrical heating conductor mounted inside said pipe and extending throughout the length of said pipe; and

c. means supporting said coils in circumferentially aligned relationship for defining the chamber volume within said coils so that heat transfer can be effected between said coils and the chamber volume.

2. A device as defined in claim 1, wherein there are two sets of pipes that are wound in the form of associated downward extending spirals to provide a bell-shaped coil arrangement about the chamber.

3. A device as in claim 2, wherein each set of pipes being wound bifilar, and between each two adjacent sides of a bifilar wound set there is disposed two adjacent sides of the other bifilar wound set so that the two sets extend parallel to one another.

4. A device as defined in claim 2, wherein said heating conductor comprises a miniature sheathed heating conductor.

5. A device as defined in claim 4, wherein the cross-sectional area of said heating conductor, corresponds substantially to a quarter of the cross-sectional area of thecavity of said cooling pipe.

6. A device as defined in claim 2, further comprising a container, closed in a vacuumtight manner, and metal strips in the form of straps for holding said cooling coil in said container.

7. A device as defined in claim 6, wherein means are provided to take the ends of said cooling pipe out of said closed container in a vacuumtight manner.

8. A device as defined in claim 7, further comprising a branchpiece'terminating each end of said cooling pipe outside said container, said heating conductor and a connection to the pipe for the introduction and removal of the cooling medium being taken out of said branchpieces and said branchpieces being spatially separated from one another.

9. A device as defined in claim 1, wherein the cooling medium consists of liquid nitrogen.

10. A device as defined in claim 1, wherein the cooling medium consists of compressed air.

11. A device as claimed in claim 1, wherein the ends of sald heating conductor taken out of said container comprise a different material from the actual heating conductor, and the resistance value of said ends of said heating conductor is as low as possible per unit of length. 

1. In a device for heating and cooling a chamber volume for use with means for circulating a cooling medium through the device and means for heating the cooling medium, the improvement comprising in combination: a. at least one pipe for conveying a circulating cooling medium and formed in the shape of helically wound coils: b. an electrical heating conductor mounted inside said pipe and extending throughout the length of said pipe; and c. means supporting said coils in circumferentially aligned relationship for defining the chamber volume within said coils so that heat transfer can be effected between said coils and the chamber volume.
 2. A device as defined in claim 1, wherein there are two sets of pipes that are wound in the form of associated downward extending spirals to provide a bell-shaped coil arrangement about the chamber.
 3. A device as in claim 2, wherein each set of pipes being wound bifilar, and between each two adjacent sides of a bifilar wound set there is disposed two adjacent sides of the other bifilar wound set so that the two sets extend parallel to one another.
 4. A device as defined in claim 2, wherein said heating conductor comprises a miniature sheaThed heating conductor.
 5. A device as defined in claim 4, wherein the cross-sectional area of said heating conductor, corresponds substantially to a quarter of the cross-sectional area of the cavity of said cooling pipe.
 6. A device as defined in claim 2, further comprising a container, closed in a vacuumtight manner, and metal strips in the form of straps for holding said cooling coil in said container.
 7. A device as defined in claim 6, wherein means are provided to take the ends of said cooling pipe out of said closed container in a vacuumtight manner.
 8. A device as defined in claim 7, further comprising a branchpiece terminating each end of said cooling pipe outside said container, said heating conductor and a connection to the pipe for the introduction and removal of the cooling medium being taken out of said branchpieces and said branchpieces being spatially separated from one another.
 9. A device as defined in claim 1, wherein the cooling medium consists of liquid nitrogen.
 10. A device as defined in claim 1, wherein the cooling medium consists of compressed air.
 11. A device as claimed in claim 1, wherein the ends of said heating conductor taken out of said container comprise a different material from the actual heating conductor, and the resistance value of said ends of said heating conductor is as low as possible per unit of length. 